Ni/Ag bimetallic nanoparticle-engineered Ti3C2Tx MXene composite as a SERS substrate for trace detection of thiram pesticide

Abstract

Surface-enhanced Raman scattering (SERS) has emerged as a powerful analytical tool for trace molecular detection, enabling identification of target analytes through their characteristic vibrational fingerprints. Its high sensitivity, selectivity, and non-destructive detection capabilities make it extremely valuable in fields such as biological detection, food safety, and environmental detection. Currently, metal carbonitride (MXene) as an emerging two-dimensional material has become a hot topic in the field of SERS. In this work, by combining the advantages of bimetallic nanoparticles and MXene nanosheets, Ni/Ag nanoparticles with different proportions were modified on monolayer MXene nanosheets through chemical reduction and transmetallation reactions for the rapid detection of thiram. The evaluation of the SERS performance of the MXene–Ni/Ag composite substrate for the Raman reporter molecule mercaptobenzoic acid (MBA) demonstrates a high SERS performance factor (SPF) of 8.2 × 10⁶, and a low detection limit of 10⁻¹⁰ M. Also, for the detection of the pesticide thiram, the substrate exhibits high sensitivity and reliable quantitative analysis capabilities, retaining detectable spectral features even at concentrations down to 10⁻⁹ M. Meanwhile, the substrate also exhibits a low relative standard deviation (RSD) value in reproducibility and maintains good stability over a certain period. Ni/Ag bimetallic nanoparticles provide high SERS activity, while MXene nanosheets effectively concentrate target molecules through their strong adsorption capacity. These results indicate that MXene–Ni/Ag composite substrates can serve as a highly effective SERS platform for sensitive and reliable environmental monitoring.